Table of Contents
Advertisement
3.11.2
Read Cache
CacheFlow implements a multiple segment read cache. Cache segments are assigned
to read commands as they are received from the host.
Each read segment consists of pre and post read sectors in addition to the host-
requested sectors. This maximizes the amount of cache data in the drive's buffer,
thereby increasing the likelihood of cache hits and improving overall performance.
3.11.3
48-bit Logical Block Addressing (LBA)
The 48-bit Address feature set allows devices with capacities up to approximately 281
tera sectors or approximately 144 peta bytes. In addition, the number of sectors that
may be transferred by a single command are increased by increasing the allowable
sector count to 16 bits.
48-bit Address
Bits (47:40)
LBA High
LBA Mid (exp)
(exp)
16-bit Sector Count
Bits (15:8)
Sector Count
Sector Count
(exp)
3.12 Power Management
The drives support the ATA power management commands that lower the average
power consumption of the hard drives. For example, to take advantage of the lower
power consumption modes of the drive, an energy efficient host system could
implement a power management scheme that issues a Standby Immediate command
when a host resident disk inactivity timer expires. The Standby Immediate command
causes the drive to spin down and enter a low-power mode. Subsequent disk access
commands would cause the drive to spin up and execute the new command.
To avoid excessive wear on the drive due to the starting and stopping of the HDA, set
the host's disk inactivity timer to no shorter than ten minutes.
The drives also support the SATA power management feature that lowers the average
power consumption of the SATA interface.
3.13 Self-Monitoring, Analysis, and Reporting Technology
(S.M.A.R.T.)
S.M.A.R.T. helps you monitor a drive's internal status through diagnostic commands at
the host level.
The drive monitors Read Error Rate, Start/Stop Count, Re-allocated Sector Count,
Seek Error Rate, Power-on Hours Count, Spin-up Retry Count, Drive Calibration Retry
Count, Drive Power Cycle Count, Offline Scan Uncorrectable Sector Count, Ultra ATA
CRC Error Rate, Multi-zone Error Rate, Spin-up Time, Relocation Event Count, and
Current Pending Sector Count. The hard drive updates and stores these attributes in
the reserved area of the disk. The drive also stores a set of attribute thresholds that
correspond to the calculated attribute values. Each attribute threshold indicates the
point at which its corresponding attribute value achieves a negative reliability status.
Product Features
Bits (39:32)
Bits (31:24)
LBA Low (exp)
Bits (7:0)
WESTERN DIGITAL CONFIDENTIAL
- 32 -
Bits (23:16)
Bits (15:8)
LBA High
LBA Mid
Bits (7:0)
LBA Low
Hide quick links:
Advertisement
Table of Contents
